An Experimental Study of Possible Post-War Ferronickel Slag Waste Disposal in Szklary (Lower Silesian, Poland) as Partial Aggregate Substitute in Concrete: Characterization of Physical, Mechanical, and Thermal Properties

Aggregates derived from waste, due to the growing awareness of global warming, are more and more often used in the concrete production process. This way, their disposal not only reduces the pollution of the Earth but also lowers the consumption of natural aggregates, which are limited. One of the new “eco” aggregates may be a ferronickel slag waste (FNSW), which was generated in post-war metallurgical processes and stored in Szklary (Lower Silesian, Poland). In order to determine the possibility of using ferronickel slag waste aggregate (FNSWA) in the concrete production process, new concrete mixtures were designed and tested. Physical properties (cone slump, air content, pH, and density), mechanical properties (compressive strength, flexural strength, and tensile strength), and thermal properties (thermal conductivity) were assessed for all new laboratory recipes. Moreover, the modulus of elasticity and Poisson’s ratio were determined. This study includes five different contents of FNSWA in the amount of 5%, 10%, 15%, 20%, and 25% of the mass of natural aggregate as its partial substitute. The final results were compared to the base sample (BS) containing 100% natural aggregate, which was granite.

Use of Glass Powder and Sand Dune in Concrete: Characterization and Performance

Cement and alluvial sand are very essential materials in concrete preparation. The first material production contributes to the emissions of greenhouse gases, in particular carbon dioxide (CO2), and the extensive exploitation of second material constitutes a danger on the extinction of its deposits. The use of waste glass powder (WGP) to partially replace cement and dune sand as a replacement for a small amount of alluvial sand appears as a potential solution that solves several problems at once (disposal of glass waste, reduction of emissions gas and preservation of construction sand deposits). The objective of this study is to verify the effects of these partial replacements on concrete properties, their cost, and the CO2 emission reduction in the atmosphere. For this, three types of concrete are prepared: a control (0% of WGP); mixture 1 (10% WGP); and mixture 2 (20% WGP). In all three types, 5% of alluvial sand is replaced by dune sand. Obtained results show that these partial replacements do not affect the porosity (less than 20%), they give good indices as to the speed of sound propagation in the concrete (up to 3500 m/s), especially for the case of the second mixture after 56 days but this does not increase the concrete performance concerning compressive strength and performance of concrete with glass is less than that of control concrete. Economically, the reduction of 10% in cement saves 5 € per ton and environmentally, it reduces the emission of CO2 from cement industry by 0.5 to 0.7% of total anthropogenic CO2 emissions.

Sustainable Development of Human Society in Terms of Natural Depleting Resources Preservation Using Natural Renewable Raw Materials in a Novel Ecological Material Production

In the last few years, the building industry experienced a significant development as a response to the demographic growth of human society and to the increasing demand for housing. Their construction involves the traditional use of concrete as a material that provides added strength to the finished building. This is manufactured respecting standard recipes depending on the way of its use. Anyway, all concrete recipes involve the use of mineral aggregates extracted from the riverbed, as is happening in Romania, or rock blocks crushing, as reported in other countries. Under these conditions, the rationalization of the use of natural mineral resources and the identification of new possibilities to reduce their consumption through their replacement with vegetal waste has become an important research issue. In this study, two types of vegetal waste—namely, shredded corn cobs and sunflower stalks—were used to manufacture novel ecological concretes. The vegetal wastes, both in untreated and treated forms (with 20% and 40% of sodium silicate solution), were used to replace 50% of the river (mineral) aggregate volume. The obtained concretes were tested, and the values of some important parameters in the concrete characterization (such as bulk density, water adsorption capacity, compressive strength and splitting tensile strength) were compared with the concrete contains cement CEM II/A-LL 42.5R. The obtained results show that these vegetal wastes have the potential to be used in the manufacturing of new ecological concrete. In addition, this alternative material meets the requirements for the sustainable and healthy development of the environment, offering low-polluting solutions in the context of an increasing demand for constructions.

Acoustic behavior of porous concrete. Characterization by experimental and inversion methods

The use of porous concrete solutions with lightweight aggregates has become increasingly common in noise control due to their versatility in exterior and interior applications. In this work, samples of porous consolidated concrete with aggregates of expanded clay were produced, in order to study the influence of the grain size, thickness and water/aggregate/cement ratio on the sound absorption. Experimental techniques were used to obtain the surface impedance and sound absorption coefficient. In addition to experimental characterizations, an inverse method was used (based on a genetic algorithm) to obtain the macroscopic parameters capable of representing the materials studied through the theoretical model of Horoshenkov-Swift. Using the theoretical Horoshenkhov-Swift model it becomes possible to represent these materials in numerical models as equivalent fluids.